Aortic valve disease (such as regurgitation or stenosis) affects over 100 million people globally, with half of them requiring implantation of a mechanical or biological aortic valve to replace the diseased valve. In 2007, there were about seventy to eighty thousand aortic valve implantation (AVI) procedures in the United States, and there is a steady growth trend. Traditionally, an AVI procedure is a complex open-heart surgical procedure. However, in recent years, the trans-catheter approach has rapidly emerged as a minimal invasive alternative for AVI procedures. In minimal invasive AVI procedures, a prosthetic valve is inserted into a patient's heart via a catheter. Intra-operative 2D X-ray imaging is used for monitoring the procedure and positioning the valve. Unfortunately, 2D X-ray projection images generally cannot distinguish soft tissue. To address this issue, image integration combining a high-resolution 3D aortic volume (which may be reconstructed from a preparatory, pre-operative imaging scan using one of the various imaging modalities, such as CT, MR, C-Arm CT, etc.) with the 2D fluoroscopic images has been developed (i.e., fluoroscopic overlay image guidance). The projection of the 3D aortic volume onto the frames of the fluoroscopy image sequence establishes a single image coordinate system and permits clearer visualization for navigating the catheter, positioning the valve and, otherwise, monitoring the procedure.
The 3D aortic volume used for the overlay is acquired either at a given cardiac and respiratory phase or during fast pacing. Consequently, the current fluoroscopic overlay techniques are usually static. In other words, the techniques do not follow the heart while the heart beats and moves through the breathing cycle. This results in apparent displacements of the static aortic volume due to cardiac motions (movement of the heart due to the cardiac cycle) and respiratory motions (respiratory-induced movement of the heart). Cardiac motion could be compensated at least partly using ECG gating, which are techniques in which image acquisition is triggered by a start pulse derived from an ECG taken from the patient during imaging.
However, breathing motion is less periodic than cardiac motion and needs to be explicitly compensated to provide for more accurate navigation. To accomplish this, a fluoroscopic overlay technique needs to generate a dynamic overlay. Motion-compensated navigation for coronary intervention was suggested in an article by Holger Timinger, Sascha Krueger, Klaus Dietmayer And Joern Borgert, entitled, “Motion Compensated Coronary Interventional Navigation by Means of Diaphram Tracking and Elastic Motion Models”, Physics in Medicine and Biology 2005, pp 491-503, Vol. 50 (No. 3). However, the proposed method is based on a magnetic tracking system for device localization using specialized catheters and, therefore, is more expensive compared to image-based localization. Image-based device localization for breathing motion compensation during hepatic artery catheterization and electrophysiology was shown in two recent articles (one article is by Selen Atasoya, Martin Grohera, Darko Zikica, Ben Glockera, Tobias Waggershauserb (MD), Marcus Pfisterc and Nassir Navaba, entitled, “Real-time Respiratory Motion Tracking: Roadmap Correction for Hepatic Artery Catheterizations”, Proceedings of Society of Photo-Optical Instrumentation Engineers (SPIE) Medical Imaging 2008, p. 691815, Vol. 6918, San Diego, Calif. USA and the other article is by Alexander Brost, Rui Liao, Joachim Hornegger and Norbert Strobel, entitled, “3-D Respiratory Motion Compensation during EP Procedures by Image-Based 3-D Lasso Catheter Model Generation and Tracking”, Medical Image Computing and Computer-Assisted Intervention—MICCAI 2009, Lecture Notes in Computer Science, September 2009, pp. 394-401, Vol. 5761).
There is a need for image-based localization for both cardiac and respiratory motion compensation during minimal invasive AVI procedures. There is also a need for such techniques that do not utilize specialized catheters and control systems.